JPH0661343A - Manufacture of semiconductor device - Google Patents

Abstract

PURPOSE:To form the element isolation region in a semiconductor device, which is provided on a semiconductor substrate with the surface consisting of a single crystal silicon layer, in an even film thickness regardless of the size of the width of the region. CONSTITUTION:A silicon dioxide film 102 is formed on a silicon substrate 101 by ion-implanting oxygen, an element isolation region formation part in a single crystal silicon layer 103 on the surface of the substrate 101 is selectively removed to form a recessed part, in which the film 102 is exposed, on the bottom of the layer 103 and a silicon dioxide film 105 is selectively formed in this recessed part by a liquid phase growth method.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method of manufacturing a semiconductor device, and more particularly to a method of forming an element isolation region.

[0002]

2. Description of the Related Art Element isolation has two main purposes. The first is to insulate elements such as transistors formed on the surface of a semiconductor substrate from each other. Second, by covering a portion such as a transistor, which is not formed on the surface of the semiconductor substrate, with a thick insulating film (several hundreds nm to 10 μm), a floating capacitance between the wiring on the insulating film and the device and the semiconductor substrate is formed. Is to reduce.

Referring to FIG. 4 which is a sectional view in the order of steps for explaining a method for manufacturing a semiconductor device, in the conventional method for forming an element isolation region, first, a silicon nitride film 202 is formed on a silicon substrate 201. To do. Next, photoresist 2
The silicon nitride 202 is patterned using 00 as a mask [FIG. 4 (a)]. Subsequently, the portion of the silicon substrate 201 not covered with the photoresist 200 is etched by isotropic etching [FIG. 4 (b)]. Next, after removing the photoresist 200, a silicon nitride film 203 is formed [FIG. 4 (c)]. Next, the silicon nitride film 203 is removed by anisotropic etching except the portion located below the silicon nitride film 202 [FIG. 4 (d)]. Next, steam oxidation is performed to convert the surface of the silicon substrate 201 not covered with the silicon nitride films 202 and 203 into a silicon dioxide film 204 [FIG. 4 (e)]. Next, the silicon nitride films 202 and 203 are removed to obtain the structure shown in FIG.

Referring to FIG. 5, which is a sectional view in order of steps for explaining a method for manufacturing a semiconductor device, another conventional method for forming an element isolation region is to pattern a photoresist 212 on a silicon substrate 211. Then, a groove is formed in the silicon substrate 211 by anisotropic etching [FIG.
(A)]. Next, a silicon dioxide film 213 is formed by chemical vapor deposition (CVD) [FIG. 5 (b)]. Next, the silicon dioxide film 213 is etched to obtain the structure shown in FIG.
The structure shown in (c) is obtained.

[0005]

The above-described conventional method for forming the element isolation region of the semiconductor device has the following drawbacks. First, in the first method, the photoresist 200
The silicon dioxide film 204 expands in the lateral direction as compared with the above pattern, increasing the width of the element isolation region. This hinders miniaturization of the semiconductor device. In the second method, when the width of the groove of the silicon substrate 211 is wide, the film thickness of the silicon dioxide film 213 becomes thin near the center of the groove. For this reason, there is a drawback that a wide element isolation region cannot be formed.

[0006]

According to a method of manufacturing a semiconductor device of the present invention, in a method of forming an element isolation region of a semiconductor device provided on a semiconductor substrate whose surface is made of single crystal silicon, element isolation on the surface of the semiconductor substrate is performed. A first step of forming a recess having a first silicon dioxide film on the bottom surface in a region where the region is formed, and a second step of burying a second silicon dioxide film by liquid phase growth in the recess. And the process.

[0007]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Next, the present invention will be described with reference to the drawings.

Referring to FIG. 1 which is a sectional view in order of steps for explaining a method for manufacturing a semiconductor device, according to a first embodiment of the present invention, first, oxygen is ion-implanted into a silicon substrate 101 (for example, energy is 200 keV). , Dose amount 10 ¹⁸ c
m ^-2 ) and the silicon dioxide film 10
2, and the single crystal silicon layer 103 is electrically separated from the silicon substrate 101 [FIG. 1 (a)].

Next, a photoresist 104 is formed on the single crystal silicon layer 103, the photoresist 104 in a portion where an element isolation region is to be formed is removed by lithography, and patterning is performed. Next, the single crystal silicon layer 103 which is not covered with the photoresist 104 is removed by anisotropic etching [FIG. 1 (b)].

Next, after removing the photoresist 104, the silicon dioxide film 105 is selectively grown by liquid phase epitaxy (LPD) only on the exposed portion of the silicon dioxide film 102, and the upper surface of the single crystal silicon layer 103 is grown. And the upper surface of the silicon dioxide film 105 are made substantially at the same height [FIG. 1 (c)].
The photoresist 104 is removed by the silicon dioxide film 1
05 It may be after formation.

The above liquid phase growth method is, for example, H ₂ SiF ₆ 4
H ₃ BO ₄ 0.6 per liter of 0 wt% aqueous solution
A film is formed by applying a wt% aqueous solution to a solution to which 10 to 50 milliliters are added per hour. At this time, the growth of the silicon dioxide film 105 by the LPD method occurs selectively only on the silicon dioxide film 102 exposed at the bottom of the recess.

Referring to FIG. 2 which is a sectional view in order of steps for explaining a method for manufacturing a semiconductor device, a second embodiment of the present invention will be described below. First, a first single crystal silicon substrate (not shown) will be described. A silicon dioxide film 111 having a film thickness of about 1 μm is formed on the surface of. Next, a second single crystal silicon substrate (not shown) is adhered to the surface of the silicon dioxide film 111, and the surface of the second single crystal silicon substrate is ground to obtain a single crystal film having a thickness of 2 to 3 μm. A crystalline silicon layer 112 is formed [FIG.
(A)]. Thereafter, the single crystal silicon layer 1 is formed by using the photoresist 113 as a mask by the same method as in the first embodiment.
12 is anisotropically etched [FIG. 2 (b)]. Next, after the photoresist 113 is removed, 2
A silicon oxide film 114 is formed [FIG. 2 (c)].

The first and second embodiments are as follows.
Although the present invention is applied to an SOI substrate, the present invention can also be applied to a semiconductor substrate having an epitaxial silicon layer on the surface of a quartz substrate.

Referring to FIG. 3 which is a sectional view in the order of steps for explaining a method for manufacturing a semiconductor device, in the third embodiment of the present invention, first, arsenic is removed from the upper surface of a p ⁻ type silicon substrate 121. Diffusion is performed to form the n ⁺ buried layer 122.
Next, an n ^- epitaxial layer 1 having a film thickness of about 1 μm is formed thereon.
23 is formed (FIG. 3A).

Next, anisotropic silicon etching is performed using the photoresist 124 as a mask to remove the n ^- epitaxial layer 123 in the portion where the element isolation region is to be formed and expose the n ⁺ buried layer 122 [FIG. 3 (b)]. .

Next, after removing the photoresist 124, thermal oxidation is performed to form a silicon dioxide film 125 on the surfaces of the n ⁻ epitaxial layer 123 and the n ⁺ buried layer 122. At this time, compared with the n ⁻ epitaxial layer 123, n ⁺
Since the buried layer 122 has a high oxidation rate, 2
The silicon oxide film 125 becomes thicker than the others [FIG.
(C)].

Next, the silicon dioxide film 125 is etched using a dilute hydrofluoric acid solution.

At this time, the etching time is such that the silicon dioxide film 125 on the n ⁻ epitaxial layer 123 is completely removed, and the silicon dioxide film 12 on the n ⁺ buried layer 122 is removed.
5 is set to the remaining condition [FIG. 3 (d)].

Next, similarly to the above first and second embodiments,
A silicon dioxide film 126 is formed by a liquid phase growth method [FIG. 3 (e)].

[0020]

As described above, according to the present invention, the second silicon dioxide film is selectively grown on the first silicon dioxide film formed at the bottom of the trench in the device isolation region. A silicon oxide film having a uniform film thickness can be obtained regardless of the size of the region width.

Further, since the method of the present invention does not cause the lateral widening of the silicon dioxide film, which has been a problem in the conventional method, an element isolation region having the same width as the patterned photoresist can be formed. . Therefore, it is possible to form an extremely thin element isolation region (processing limit of photoresist). As a result, there is an effect that high integration of the semiconductor device and reduction of wiring length due to high integration, reduction of parasitic capacitance, and high performance by reduction of resistance are possible.

[Brief description of drawings]

1A to 1D are cross-sectional views in order of processes for explaining a first embodiment of the present invention.

2A to 2D are cross-sectional views in order of a process, for illustrating a second embodiment of the present invention.

FIG. 3 is a cross-sectional view in process order for explaining a third embodiment of the present invention.

4A to 4C are cross-sectional views in order of processes for explaining a conventional method for manufacturing a semiconductor device.

FIG. 5 is a cross-sectional view in process order for explaining another conventional method for manufacturing a semiconductor device.

[Explanation of symbols]

101, 121, 201, 211 Silicon substrate 102, 105, 111, 114, 125, 126, 2
04,213 silicon dioxide film 103,112 single crystal silicon layer 104,113,124,200,212 photoresist 122 n ⁺ buried layer 123 n ^- epitaxial layer 202,203 silicon nitride film

Claims (6)

[Claims] 1. A method of forming an element isolation region of a semiconductor device, the surface of which is provided on a semiconductor substrate made of single crystal silicon, comprising: a first surface on a bottom surface of the semiconductor substrate on which the element isolation region is formed. 1. A method of manufacturing a semiconductor device, comprising: a first step of forming a concave portion having a silicon dioxide film of 2; and a step of filling the concave portion with a second silicon dioxide film of a liquid phase growth method. . 2. The semiconductor substrate is a single crystal silicon substrate having a silicon dioxide layer formed by ion implantation of oxygen to a predetermined depth, and the first silicon dioxide film is formed of the silicon dioxide film. The method of manufacturing a semiconductor device according to claim 1, further comprising: being a silicon oxide layer. 3. The semiconductor substrate comprises a first single crystal silicon substrate, the first silicon dioxide film formed on the surface of the first single crystal silicon substrate, and the first silicon dioxide. 2. The method of manufacturing a semiconductor device according to claim 1, comprising a second single crystal silicon substrate adhered to the surface of the film. 4. The method of manufacturing a semiconductor device according to claim 1, wherein the semiconductor substrate comprises a quartz substrate and an epitaxial silicon layer formed on the surface of the quartz substrate. 5. The semiconductor substrate comprises one conductivity type single crystal silicon substrate, a high concentration reverse conductivity type buried layer formed on a surface of the one conductivity type single crystal silicon substrate, and the high concentration A low-concentration reverse-conductivity-type single-crystal silicon layer provided on the surface of the reverse-conductivity-type buried layer; and the first step includes forming the element isolation region on the surface of the single-crystal silicon layer. In the region where the bottom surface is formed of the high-concentration reverse conductivity type buried layer, a surface of the high-concentration reverse conductivity type buried layer exposed on the bottom surface of the recess, and Forming a silicon dioxide film by thermal oxidation on the surface of the single crystal silicon layer; removing the silicon dioxide film by thermal oxidation until the upper surface of the single crystal silicon layer is exposed, and exposing the bottom surface of the recess. Said Takano 2. The semiconductor device according to claim 1, further comprising the step of forming the first silicon dioxide film made of the silicon dioxide film by the thermal oxidation on the surface of the reverse conductivity type buried layer. Manufacturing method. 6. The method according to claim 1, wherein the second step is performed in an aqueous solution containing at least fluorine, and the second silicon dioxide film contains fluorine. A method for manufacturing a semiconductor device as described above.